In recent years, attention has been given to electric power feed systems (noncontact electric power feed systems and wireless charging systems) performing noncontact electric power supply (electric power transmission) to, for example, CE devices (Consumer Electronics Devices) including cellular phones and portable music players. These electric power feed systems are allowed to start charge only through placing an electronic apparatus (a secondary-side apparatus) on a charging tray (a primary-side apparatus), instead of starting charge through inserting (connecting) a connector of a power supply apparatus such as an AC adapter into the electronic apparatus. In other words, terminal connection between the electronic apparatus and the charging tray is not necessary.
As a system performing noncontact electric power supply in such a manner, an electromagnetic induction type is well known. Moreover, recently, attention has been given to noncontact electric power feed systems with use of a type called a magnetic resonance type employing an electromagnetic resonance phenomenon.
At present, in electromagnetic induction type noncontact electric power feed systems which have been already widely used, an electric power feed source (an electric power transmission coil) and an electric power destination (an electric power reception coil) need to share a magnetic flux. Therefore, to efficiently perform electric power supply, the electric power feed source and the electric power destination need to be disposed extremely close to each other, and axis alignment for coupling is also important.
On the other hand, noncontact electric power feed systems employing the electromagnetic resonance phenomenon have an advantage, based on the principle of the electromagnetic resonance phenomenon, that electric power is allowed to be transmitted to a longer distance, compared to the electromagnetic induction type, and even if axis alignment is slightly insufficient, transmission efficiency is not reduced so much. It is to be noted that types employing the electromagnetic resonance phenomenon include an electric resonance type, in addition to the magnetic resonance type. In noncontact electric power feed systems with use of the magnetic resonance type (for example, refer to PTL 1 and PTL 2), strict axis alignment is not necessary, and an electric power feeding distance is allowed to be increased.